EP0043456B1 - Machine element composed of ceramic oxide material - Google Patents

Machine element composed of ceramic oxide material Download PDF

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Publication number
EP0043456B1
EP0043456B1 EP19810104408 EP81104408A EP0043456B1 EP 0043456 B1 EP0043456 B1 EP 0043456B1 EP 19810104408 EP19810104408 EP 19810104408 EP 81104408 A EP81104408 A EP 81104408A EP 0043456 B1 EP0043456 B1 EP 0043456B1
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EP
European Patent Office
Prior art keywords
mechanical component
oxide
weight
valve
machine components
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
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EP19810104408
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German (de)
French (fr)
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EP0043456A1 (en
Inventor
Ulf Dr. Dipl.-Mineraloge Dworak
Hans Jud
Hans Dr. Dipl.-Chem. Olapinski
Dieter Dr. Dipl.-Ing. Fingerle
Ulrich Dr. Dipl.-Ing. Krohn
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CESSIONE;CERASIV GMBH INNOVATIVE KERAMIK - ENGINEE
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Feldmuehle AG
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
    • F16K25/00—Details relating to contact between valve members and seats
    • F16K25/005—Particular materials for seats or closure elements
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/10—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on aluminium oxide
    • C04B35/111—Fine ceramics
    • C04B35/117—Composites
    • C04B35/119—Composites with zirconium oxide
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/16—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on silicates other than clay
    • C04B35/18—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on silicates other than clay rich in aluminium oxide
    • C04B35/185—Mullite 3Al2O3-2SiO2
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
    • F16K11/00—Multiple-way valves, e.g. mixing valves; Pipe fittings incorporating such valves
    • F16K11/02—Multiple-way valves, e.g. mixing valves; Pipe fittings incorporating such valves with all movable sealing faces moving as one unit
    • F16K11/06—Multiple-way valves, e.g. mixing valves; Pipe fittings incorporating such valves with all movable sealing faces moving as one unit comprising only sliding valves, i.e. sliding closure elements
    • F16K11/072—Multiple-way valves, e.g. mixing valves; Pipe fittings incorporating such valves with all movable sealing faces moving as one unit comprising only sliding valves, i.e. sliding closure elements with pivoted closure members
    • F16K11/074—Multiple-way valves, e.g. mixing valves; Pipe fittings incorporating such valves with all movable sealing faces moving as one unit comprising only sliding valves, i.e. sliding closure elements with pivoted closure members with flat sealing faces
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T137/00—Fluid handling
    • Y10T137/8593—Systems
    • Y10T137/86493—Multi-way valve unit
    • Y10T137/86815—Multiple inlet with single outlet
    • Y10T137/86823—Rotary valve

Definitions

  • the present invention relates to a machine component made of oxide ceramic material components, which has a sealing effect and is in frictional engagement, such as. B. slide ring for axial slide bearing seals or valve disc for mixing valves, in particular valve disc for sanitary mixer taps.
  • Machine components made of oxide ceramic materials such as B. valve disks, which are used in preferably consisting of two such valve disks control elements, such as are installed in mixing valves, but in particular in mixer taps of the sanitary area for regulating liquid flows, are known.
  • B. valve disks which are used in preferably consisting of two such valve disks control elements, such as are installed in mixing valves, but in particular in mixer taps of the sanitary area for regulating liquid flows, are known.
  • a ceramic valve seat which consists of 85-99% by weight of aluminum oxide and 1-4% by weight of talc.
  • such a valve seat contains 6% by weight of kaolin with a corresponding reduction in the aluminum oxide content.
  • valve parts From FR-A-14 54 755 the production of such valve parts is also known from mixtures which, in addition to 35 to 70% by weight of zirconium oxide, also 7 to 30% by weight of calcium and zirconium silicate, 0 to 30% by weight of magnesium and zirconium silicate , 0 to 25% by weight of pottery clay and 0 to 25% by weight of kaolin.
  • zirconium oxide also 7 to 30% by weight of calcium and zirconium silicate, 0 to 30% by weight of magnesium and zirconium silicate , 0 to 25% by weight of pottery clay and 0 to 25% by weight of kaolin.
  • the advantage of these known ceramic valve disks is the improved abrasion resistance and the greater resistance to erosion and corrosion compared to valve parts made from hard metals.
  • valve disks made of 95 to 100% by weight aluminum oxide, 0 to 3% by weight talc and 0 to 3% by weight kaolin improve that the mutually engaging sides of the valve discs are lapped and polished so that they have a flatness of 3 light bands and a surface quality with a square mean (geometric mean roughness) ⁇ 10.
  • the machine components known up to now are assessed by determining the proportion of profile load.
  • the profile load share which has long been known in wide areas of technology in which the assessment of the surface quality plays an important role, is the ratio of the load-bearing length to the reference distance.
  • the necessary tightness could only be achieved by a high proportion of profile support.
  • the previously known valve disks and slide rings have a load share> 70%.
  • the amount of the supporting portion also increases the force required, for example, to move two engaging valve disks against one another.
  • the disadvantage resulting from the high displacement force to be exerted for the user is e.g. B. a sanitary mixer tap, especially in older valves that a fine regulation and mixing of hot and cold water flows is not possible straight away and the setting may therefore need to be corrected several times.
  • the object of the present invention is to overcome these existing disadvantages.
  • the invention seeks to create machine components which are in frictional engagement and have a completely sealing effect, but which are nevertheless easily displaceable relative to the machine parts with which they are in engagement.
  • Valve disks manufactured according to the invention should have a better metering possibility due to the easy displaceability of the valve disks, this adjustability being to be retained even after a long period of operation.
  • Other properties, such as good thermal shock resistance, must not be adversely affected.
  • Slide rings manufactured according to the invention are said to have better emergency running properties with a lower dry-running temperature.
  • the invention is described below using the example of zirconium oxide, but it also applies analogously to hafnium oxide, especially since the types of zirconium oxide on the market often contain traces of hafnium oxide.
  • the present invention is based on the property of the zirconium oxide and / or hafnium oxide to convert from the metastable tetragonal modification at temperatures below approximately 1100 ° C.
  • DE-A-2744700 the applicant has only recently proposed a sintered material based on dense, non-metallic hard materials, such as high-melting metal carbides, metal nitrides, metal borides and metal oxides, in which, although with a completely different objective, the property of the phase change of the Zirconium and / or hafnium oxide is used.
  • the outstanding effect of the present invention is based on the fact that the zirconium oxide is present in a monoclinic modification on the surface of the machine component.
  • the surface is to be understood as the functional surface to be brought into engagement with another machine component.
  • this is e.g. B. the surface of another valve disc.
  • a slide ring it is a machine component lying against the end face of the slide ring, e.g. B. from a self-lubricating sliding material, such as. B. coal or phenolic resin or a machine component that is made of the same material as the slide ring.
  • the desired load share can be achieved at a required average roughness Ra of z. B. 0.1 microns can be set by the material composition. For a given mechanical action, micro-breakouts occur as a result of the voltage-induced phase transition of the zirconium oxide particles lying on or immediately below the surface.
  • the grain breakout size has become controllable through the shape and number of grain size, grain distribution and the amount of zirconium oxide incorporated and enables the desired low roughness to be achieved in conjunction with a desired low profile load share.
  • the flatness of the machine components according to the invention is quite comparable to that of the known machine components.
  • the roughness, by which the arithmetic mean roughness Ra according to DIN 4762 is to be understood, is considerably lower.
  • the main difference to the previously known machine components, however, consists in a reduced profile load share down to the 8th part.
  • the profile load share tp is determined by evaluating profile sections.
  • the proportion of profile load is determined in deviation from the DIN standard mentioned by evaluating photographic recordings (reflected light microscopy). Here, all depressions in the surface (all non-flat areas) appear as dark zones due to the non-directional light backscattering.
  • Another advantage of the novel microstructure of the surface of the machine components according to the invention is that they can be used without additional grease, their full functionality being retained even after a long period of time.
  • the machine components according to the invention contain 7 to 16% by weight of zirconium oxide.
  • the average roughness Ra is preferably between 0.1 and 0.03 ⁇ m.
  • the machine components according to the invention can contain aluminum oxide, titanium oxide and mullite as further oxide-ceramic materials, very particularly preferred is the aluminum oxide, which is advantageously contained at least 75% by weight.
  • a particle size of ⁇ 5 ⁇ m and for the zirconium oxide a particle size of 0.2 to 2 ⁇ m have proven to be optimally suitable for achieving the desired surface characteristics.
  • Small amounts of a grain growth inhibitor and sintering aid can also be added to the aluminum oxide, a quantity of 0.05 to 0.25% by weight of magnesium oxide being particularly suitable.
  • the machine components according to the invention differ from those previously known in that the surface does not have the high-gloss appearance of the previously known machine components, but has a more matt-gloss appearance.
  • the differences that can already be seen externally with the naked eye can be attributed to the different microstructure of the surface, with a high proportion of profile support resulting in a high-gloss surface, while a low proportion of support with a large number of cuts - but of very small depth - gives the machine components according to the invention a matt-glossy appearance of the surface gives.
  • this different structure in the surface can only be achieved if the surface is processed in such a way that a conversion of the incorporated zirconium oxide into the monoclinic form actually takes place on the surface of the machine components according to the invention.
  • This conversion of the embedded zirconium oxide particles located on the surface or immediately below the surface takes place due to the stress-induced phase transition as a result of the high mechanical / thermal stress on the incorporated zirconium oxide particles, which becomes effective in this surface area during processing with diamond grain (grinding and / or lapping) their immediate surroundings.
  • the embedded zirconium oxide particles located deeper inside the machine components remain in the metastable tetragonal modification, since on the one hand the mechanical / thermal load applied by the grinding or lapping process decreases sharply at greater depth and on the other hand the folding of these tetragonal zirconium oxide particles into the monoclinic modification, which takes place with an increase in volume, is hindered by the strong all-round integration of the particles (compressive forces) in the other material components.
  • the figure shows a machine component in the form of a valve disk in the composition according to the invention, without the invention being restricted to this embodiment.
  • valve disk is designated by 1. At the edge, the valve disk 1 has recesses 2. With 3 or 3 'the passage openings for the liquid streams to be mixed and with 4 the outlet of the mixed liquid stream are designated. 5 shows the interior of the valve disc in a schematic form, in which the embedded zirconium oxide is present in a metastable, tetragonal modification at room temperature.
  • the disks are fired in a gas-heated furnace at a temperature of 1,550 ° C. and a holding time at this temperature of 3 hours to form dense bodies. These bodies have as a result of the reaction the final composition: mullite + zirconium oxide and excess aluminum oxide.
  • valve discs After lapping with 5 ⁇ m diamond grain on a grooved, flat steel disc, the valve discs have a matt, glossy surface with an extremely low profile percentage, which was determined to be 15% by optical analysis.
  • the center roughness Ra was measured at 0.05 ⁇ m.
  • an aluminum oxide powder suitable for the production of sintered, high-density and fine-grained A1 2 0 5 ceramic with an addition of 0.1% by weight of magnesium oxide and an average particle size of ⁇ 5 ⁇ m are mixed with 100 g of monoclinic (unstabilized) zirconium oxide powder with a average particle size of ⁇ 1 ⁇ m ground and mixed with the addition of water.
  • the ground slip is spray-dried with the addition of a conventional water-soluble binder.
  • the granules obtained in this way are pressed at a pressure of approximately 1,500 kg / cm 2 in a hydraulic, axially acting press to form a valve disk as shown in the figure.
  • This valve disc is densely sintered in a gas-heated furnace at a temperature of 1,600 ° C. and a holding time at this temperature of 5 hours.
  • the flatness of the machined valve disks is ⁇ 2 light bands.
  • a valve disk manufactured according to Example 2 was compared with a valve disk of identical shape made of pure aluminum oxide ceramic for its thermal shock behavior.
  • the measured thermal shock resistance of the pure aluminum oxide ceramic disc was ⁇ T 110 ° C, while the valve disc according to Example 2 had a thermal shock resistance of ⁇ T 110 ° C.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Organic Chemistry (AREA)
  • Structural Engineering (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • Composite Materials (AREA)
  • Compositions Of Oxide Ceramics (AREA)
  • Sliding Valves (AREA)
  • Multiple-Way Valves (AREA)
  • Sliding-Contact Bearings (AREA)

Description

Die vorliegende Erfindung betrifft ein Maschinenbauteil aus oxidkeramischen Werkstoffkomponenten, das abdichtend wirkt und in reibendem Eingriff steht, wie z. B. Gleitring für axiale Gleitlagerdichtungen oder Ventilscheibe für Mischventile, insbesondere Ventilscheibe für sanitäre Mischbatterien.The present invention relates to a machine component made of oxide ceramic material components, which has a sealing effect and is in frictional engagement, such as. B. slide ring for axial slide bearing seals or valve disc for mixing valves, in particular valve disc for sanitary mixer taps.

Maschinenbauteile aus oxidkeramischen Werkstoffen wie z. B. Ventilscheiben, die in vorzugsweise aus zwei solcher Ventilscheiben bestehenden Steuerelementen verwendet werden, wie sie in Mischventilen, insbesondere aber in Mischbatterien des Sanitärbereiches zur Regulierung von Flüssigkeitsströmen eingebaut werden, sind bekannt. In der DE-B-1282377 ist z. B. ein keramischer Ventilsitz beschrieben, der aus 85-99 Gew.% Aluminiumoxid und 1-4 Gew.% Talk besteht. In bevorzugter Ausführung enthält ein solcher Ventilsitz 6 Gew.% Kaolin bei entsprechender Reduzierung des Aluminiumoxidanteils.Machine components made of oxide ceramic materials such as B. valve disks, which are used in preferably consisting of two such valve disks control elements, such as are installed in mixing valves, but in particular in mixer taps of the sanitary area for regulating liquid flows, are known. In DE-B-1282377 z. B. describes a ceramic valve seat, which consists of 85-99% by weight of aluminum oxide and 1-4% by weight of talc. In a preferred embodiment, such a valve seat contains 6% by weight of kaolin with a corresponding reduction in the aluminum oxide content.

Aus der FR-A-14 54 755 ist die Herstellung solcher Ventilteile auch aus Mischungen bekannt, die neben 35 bis 70 Gew.% Zirkonoxid noch 7 bis 30 Gew.% Calzium- und Zirkonsilikat, 0 bis 30 Gew.% Magnesium- und Zirkonsilikat, 0 bis 25 Gew.% Töpferton und 0 bis 25 Gew.% Kaolin enthalten. Der Vorteil dieser bekannten keramischen Ventilscheiben liegt in der verbesserten Abriebbeständigkeit und der größeren Beständigkeit gegen Erosion und Korrosion gegenüber aus Hartmetallen hergestellten Ventilteilen. Ein weiterer Vorschlag, wie er in der DE-B-1291 957 enthalten ist, geht dahin, die Abdichtwirkung von Ventilscheiben aus 95 bis 100 Gew.% Aluminiumoxid, 0 bis 3 Gew.% Talk und 0 bis 3 Gew.% Kaolin dadurch zu verbessern, daß die miteinander in Eingriff stehenden Seiten der Ventilscheiben so geläppt und poliert werden, daß sie eine Ebenheit von 3 Lichtbanden und eine Oberflächenbeschaffenheit mit einem quadratischen Mittelwert (geometrischer Mittenrauhwert) < 10 aufweisen.From FR-A-14 54 755 the production of such valve parts is also known from mixtures which, in addition to 35 to 70% by weight of zirconium oxide, also 7 to 30% by weight of calcium and zirconium silicate, 0 to 30% by weight of magnesium and zirconium silicate , 0 to 25% by weight of pottery clay and 0 to 25% by weight of kaolin. The advantage of these known ceramic valve disks is the improved abrasion resistance and the greater resistance to erosion and corrosion compared to valve parts made from hard metals. Another proposal, as contained in DE-B-1291 957, is to increase the sealing effect of valve disks made of 95 to 100% by weight aluminum oxide, 0 to 3% by weight talc and 0 to 3% by weight kaolin improve that the mutually engaging sides of the valve discs are lapped and polished so that they have a flatness of 3 light bands and a surface quality with a square mean (geometric mean roughness) <10.

Neben diesen, die Qualität eines keramischen Maschinenbauteils wie Ventildichtscheiben und Gleitringe kennzeichnenden Bezugsgrößen werden die bis jetzt bekannten Maschinenbauteile durch die Festlegung des Profiltraganteils beurteilt. Unter dem Profiltraganteil, der in weiten Bereichen der Technik, in denen die Beurteilung der Oberflächengüte eine wichtige Rolle spielt, seit langem bekannt ist, versteht man gemäß DIN 4762 das Verhältnis der tragenden Länge zur Bezugsstrecke. Bei der Herstellung von abdichtenden und in reibendem Eingriff stehenden Maschinenbauteilen war man bisher davon ausgegangen, daß die notwendige Dichtigkeit nur durch einen hohen Profiltraganteil erzielt werden kann. In der Tat weisen die bisher bekannten Ventilscheiben und Gleitringe Traganteile > 70 % auf. Mit der Höhe des Traganteiles nimmt jedoch auch die Kraft zu, die beispielsweise zur Gegeneinanderverschiebung zweier in Eingriff stehender Ventilscheiben erforderlich ist. Bei den bekannten Ventilscheiben ist infolge ihres hohen Profiltraganteils daher auch eine hohe Verschiebekraft notwendig. Um den Nachteil der hohen Verschiebekraft auszugleichen, behilft man sich nach wie vor damit, bei der Montage der Steuerelemente etwas Fett, zumeist auf Silikonbasis, zwischen die Ventilscheiben zu schmieren. Das eingebrachte Fett befindet sich dabei zunächst in sogenannten Schmiertaschen, das sind Vertiefungen auf der Oberfläche der Ventilscheiben. Durch den Einfluß des Wassers ist die Wirkung des Fettes jedoch nicht von Dauer und schließlich nicht mehr vorhanden. Von diesem Moment an muß eine höhere Verschiebekraft aufgewendet werden und es setzt ein erhöhter Verschleiß ein, da im Wasser befindliche Verunreinigungen, wie z. B. Sand, die glatten Oberflächen der flächig aufeinanderliegenden Ventilscheiben mehr und mehr beschädigen.In addition to these reference values, which characterize the quality of a ceramic machine component such as valve sealing washers and slide rings, the machine components known up to now are assessed by determining the proportion of profile load. According to DIN 4762, the profile load share, which has long been known in wide areas of technology in which the assessment of the surface quality plays an important role, is the ratio of the load-bearing length to the reference distance. In the manufacture of sealing machine components that are in frictional engagement, it was previously assumed that the necessary tightness could only be achieved by a high proportion of profile support. In fact, the previously known valve disks and slide rings have a load share> 70%. However, the amount of the supporting portion also increases the force required, for example, to move two engaging valve disks against one another. In the known valve disks, a high displacement force is therefore also necessary due to their high proportion of profile support. In order to compensate for the disadvantage of the high displacement force, one still helps by greasing some grease, usually silicone-based, between the valve disks when installing the control elements. The grease introduced is initially in so-called lubrication pockets, which are depressions on the surface of the valve disks. Due to the influence of water, the effect of the fat is not permanent and ultimately no longer exists. From this moment on, a higher displacement force has to be applied and increased wear occurs because contaminants in the water, such as e.g. B. sand, the smooth surfaces of the flat superimposed valve disks more and more damage.

Der durch die aufzuwendende hohe Verschiebekraft entstehende Nachteil besteht für den Benutzer z. B. einer sanitären Mischarmatur, insbesondere bei älteren Armaturen darin, daß eine feine Regulierung und Mischung von Heiß- und Kaltwasserströmen nicht auf Anhieb möglich ist und die Einstellung deshalb unter Umständen mehrfach korrigiert werden muß.The disadvantage resulting from the high displacement force to be exerted for the user is e.g. B. a sanitary mixer tap, especially in older valves that a fine regulation and mixing of hot and cold water flows is not possible straight away and the setting may therefore need to be corrected several times.

Man hat auch bereits versucht, den Profiltraganteil der Ventilscheiben durch Schleifen mit gröberem Diamantkorn zu reduzieren. Auch diese Maßnahme brachte noch nicht den gewünschten Erfolg, weil bei einem auf diese Weise erzeugten geringeren Profiltraganteil von z. B. < 40 % die Dichtungswirkung der Steuerelemente nachläßt. Die Nachteile der bisher bekannten Gleitringe liegen darin, daß durch zu hohen Traganteil die Trockenreibung zunimmt und damit Trockenlauftemperature über 300 °C auftreten.Attempts have also already been made to reduce the proportion of profile support in the valve disks by grinding with coarser diamond grit. This measure also did not bring the desired success, because with a lower profile load share of z. B. <40% the sealing effect of the control elements decreases. The disadvantages of the slide rings known to date are that the dry friction increases due to a too high load-bearing component and dry-running temperatures above 300 ° C. occur.

Die Aufgabe der vorliegenden Erfindung ist die Überwindung dieser bestehenden Nachteile. Insbesondere will die Erfindung Maschinenbauteile schaffen, die in reibendem Eingriff stehen und vollkommen abdichtend wirken, die aber trotzdem leicht gegenüber den Maschinenteilen, mit denen sie in Eingriff stehen, verschiebbar sind. Entsprechend der Erfindung hergestellte Ventilscheiben sollen infolge der leichten Verschiebbarkeit der Ventilscheiben eine bessere Dosiermöglichkeit aufweisen, wobei diese Einstellungsfähigkeit auch nach langer Betriebsdauer erhalten bleiben soll. Dafür dürfen andere Eigenschaften wie insbesondere eine gute Thermoschockfestigkeit keinesfalls nachteilig beeinflußt werden. Entsprechend der Erfindung hergestellte Gleitringe sollen eine bessere Notlaufeigenschaft bei gleichzeitig niedrigerer Trockenlauftemperatur besitzen.The object of the present invention is to overcome these existing disadvantages. In particular, the invention seeks to create machine components which are in frictional engagement and have a completely sealing effect, but which are nevertheless easily displaceable relative to the machine parts with which they are in engagement. Valve disks manufactured according to the invention should have a better metering possibility due to the easy displaceability of the valve disks, this adjustability being to be retained even after a long period of operation. Other properties, such as good thermal shock resistance, must not be adversely affected. Slide rings manufactured according to the invention are said to have better emergency running properties with a lower dry-running temperature.

Die Lösung der Aufgabe gelingt durch ein aus oxidkeramischen Werkstoffkomponenten hergestelltes Maschinenbauteil, das durch die folgenden Merkmale gekennzeichnet ist:

  • a) Das Maschinenbauteil enthält 3,0 bis 25 Gew.% Zirkonoxid und/oder Hafniumoxid, die in die übrigen Werkstoffkomponenten in homogener Verteilung eingelagert sind und im Inneren des Maschinenbauteils zu überwiegendem Teil bei Raumtemperatur in metastabiler, tetragonaler Modifikation, and der Oberfläche des Maschinenbauteils jedoch in monokliner Modifikation vorliegen,
  • b) einen durch Oberflächenbehandlung wie Schleifen und Läppen erhaltenen Profiltraganteil von 10 bis 40%,
  • c) einen Mittenrauhwert Ra des Maschinenbauteils kleiner als 0,3 µm.
The task is solved by a machine component made of oxide-ceramic material components, which is characterized by the following features:
  • a) The machine component contains 3.0 to 25% by weight of zirconium oxide and / or hafnium oxide, which are embedded in the other material components in a homogeneous distribution and to a large extent inside the machine component at room temperature in a metastable, tetragonal modification, on the surface of the machine component but in a monoclinic modification,
  • b) a 10 to 40% proportion of the profile support obtained by surface treatment such as grinding and lapping,
  • c) an average roughness R a of the machine component of less than 0.3 μm.

Zur Vereinfachung wird nachfolgend die Erfindung am Beispiel des Zirkonoxids beschrieben, sie gilt sinngemäß aber auch für das Hafniumoxid, zumal die im Handel befindlichen Zirkonoxidsorten vielfach Spuren von Hafniumoxid enthalten.To simplify matters, the invention is described below using the example of zirconium oxide, but it also applies analogously to hafnium oxide, especially since the types of zirconium oxide on the market often contain traces of hafnium oxide.

Die vorliegende Erfindung beruht auf der Eigenschaft des Zirkon- und/oder Hafniumoxids, sich bei Temperaturen unterhalb ca 1 100 °C aus der metastabilen tetragonalen Modifikation umzuwandeln. In der DE-A-2744700 hat die Anmelderin erst kürzlich einen Sinterwerkstoff auf Basis von dichten, nichtmetallischen Hartstoffen, wie hochschmelzenden Metallcarbiden, Metallnitriden, Metallboriden und Metalloxiden in Vorschlag gebracht, bei dem, wenn auch mit gänzlich anderer Zielsetzung, die Eigenschaft der Phasenumwandlung des Zirkon- und/oder Hafniumoxids ausgenutzt wird. Es handelt sich dabei um die Verbesserung von Bruchzähigkeit und Biegefestigkeit von Sinterwerkstoffen der oben beschriebenen Art, in die feine Teilchen von Zirkon- und/oder Hafniumoxid eingelagert sind, die sich bei mechanischer Beanspruchung aus der metastabilen tetragonalen Modifikation in die monokline Form umwandeln und wobei durch diese Phasenumwandlung Spannungen abgebaut werden.The present invention is based on the property of the zirconium oxide and / or hafnium oxide to convert from the metastable tetragonal modification at temperatures below approximately 1100 ° C. In DE-A-2744700, the applicant has only recently proposed a sintered material based on dense, non-metallic hard materials, such as high-melting metal carbides, metal nitrides, metal borides and metal oxides, in which, although with a completely different objective, the property of the phase change of the Zirconium and / or hafnium oxide is used. It is about the improvement of fracture toughness and flexural strength of sintered materials of the type described above, in which fine particles of zirconium and / or hafnium oxide are embedded, which convert under mechanical stress from the metastable tetragonal modification into the monoclinic form and thereby through this phase change voltages are reduced.

Die hervorragende Wirkung der vorliegenden Erfindung beruht darauf, daß an der Oberfläche des Maschinenbauteils das Zirkonoxid in monokliner Modifikation vorliegt. Unter der Oberfläche ist dabei die mit einem anderen Maschinenbauteil in Eingriff zu bringende Funktionsfläche zu verstehen. Bei einer Ventilscheibe ist dies z. B. die Oberfläche einer weiteren Ventilscheibe. Bei einem Gleitring ist es ein gegen die Stirnfläche des Gleitringes liegendes Maschinenbauteil, z. B. aus einem selbstschmierenden Gleitwerkstoff, wie z. B. Kohle oder Phenolharz oder auch ein Maschinenbauteil, das aus dem gleichen Werkstoff hergestellt ist wie der Gleitring.The outstanding effect of the present invention is based on the fact that the zirconium oxide is present in a monoclinic modification on the surface of the machine component. The surface is to be understood as the functional surface to be brought into engagement with another machine component. For a valve disc, this is e.g. B. the surface of another valve disc. In the case of a slide ring, it is a machine component lying against the end face of the slide ring, e.g. B. from a self-lubricating sliding material, such as. B. coal or phenolic resin or a machine component that is made of the same material as the slide ring.

Die Umwandlung aus der metastabilen tetragonalen Modifikation erfolgt durch die in üblicher Weise im Anschluß an das Sintern durchgeführte Oberflächenbearbeitung, wie z. B. durch Schleifen oder Läppen, bzw. durch die dabei auftretende mechanische Beanspruchung. Der entscheidene Vorteil gegenüber den bekannten Maschinenbauteilen, wie z. B. Ventilscheiben aus 99 Gew.% Aluminiumoxid mit geringen Zusätzen von Magnesiumoxid ist nicht in allen Einzelheiten geklärt, erklärt sich jedoch voraussichtlich wie folgt :

  • Im Fall der bekannten Maschinenbauteile ist die Realisierung geringer Traganteile an eine relativ grobe Bearbeitung (grobes Schleifkorn) gebunden, was zu hohen Mittenrauhwerten und letztlich zu Problemen bei der Dichtigkeit führt.
The conversion from the metastable tetragonal modification is carried out by the surface treatment carried out in the customary manner after the sintering, such as, for. B. by grinding or lapping, or by the resulting mechanical stress. The decisive advantage over the known machine components, such as. B. Valve disks made of 99% by weight aluminum oxide with small additions of magnesium oxide have not been clarified in detail, but are probably explained as follows:
  • In the case of the known machine components, the realization of small load-bearing components is tied to a relatively rough machining (coarse abrasive grain), which leads to high mean roughness values and ultimately to problems with tightness.

Bei den erfindungsgemäßen Maschinenbauteilen kann der gewünschte Traganteil bei einem geforderten Mittenrauhwert Ra von z. B. 0,1 µm durch die Werkstoffzusammensetzung eingestellt werden. Bei gegebener mechanischer Einwirkung kommt es infolge der spannungsinduzierten Phasenumwandlung der an bzw. Unmittelbar unter der Oberfläche liegenden eingelagerten Zirkonoxidteilchen zu Mikroausbrüchen. Die Kornausbruchsgröße ist dabei durch Gestalt und Anzahl von Korngröße, Kornverteilung und Menge des eingelagerten Zirkonoxidanteils kontrollierbar geworden und ermöglicht die bisher nicht herzustellende Erzielung einer gewünschten geringen Rauhigkeit in Verbindung mit einem gewünschten geringen Profiltraganteil.In the machine components according to the invention, the desired load share can be achieved at a required average roughness Ra of z. B. 0.1 microns can be set by the material composition. For a given mechanical action, micro-breakouts occur as a result of the voltage-induced phase transition of the zirconium oxide particles lying on or immediately below the surface. The grain breakout size has become controllable through the shape and number of grain size, grain distribution and the amount of zirconium oxide incorporated and enables the desired low roughness to be achieved in conjunction with a desired low profile load share.

Zwischen den Oberflächen der erfindungsgemäßen und denen der bekannten Maschinenbauteile besteht demnach ein fundamentaler Unterschied. Während die bekannten Maschinenbauteile « größere ebene Flächen aufweisen, die nur gelegentlich von wenigen, allerdings « größeren Einschnitten unerbrochen sind, kann die Mikrostruktur der erfindungsgemäßen Maschinenbauteile wie folgt beschrieben werden :

  • Eine Vielzahl von Höhen und Tiefen, deren Differenz zur Einschnittiefe der bekannten Maschinenbauteile außerordentlich klein ist.
There is therefore a fundamental difference between the surfaces of the machine components according to the invention and those of the known machine components. While the known machine components have "larger flat surfaces that are only occasionally broken by a few, but" larger incisions, the microstructure of the machine components according to the invention can be described as follows:
  • A variety of heights and depths, the difference to the cutting depth of the known machine components is extremely small.

Die Ebenheit der erfindungsgemäßen Maschinenbauteile ist durchaus mit derjenigen der bekannten Maschinenbauteile vergleichbar. Die Rauhigkeit, unter der der arithmetische Mittenrauhwert Ra gemäß DIN 4762 zu verstehen ist, ist dagegen erheblich geringer. Der wesentliche Unterschied zu den bisher bekannten Maschinenbauteilen besteht aber in einem bis zu etwa auf den 8.Teil reduzierten Profiltraganteil.The flatness of the machine components according to the invention is quite comparable to that of the known machine components. The roughness, by which the arithmetic mean roughness Ra according to DIN 4762 is to be understood, is considerably lower. The main difference to the previously known machine components, however, consists in a reduced profile load share down to the 8th part.

Gemäß DIN 4762 erfolgt die Bestimmung des Profiltraganteils tp durch die Auswertung von Profilschnitten. Bei Oberflächen mit extrem feinen Ausbrüchen bzw. Vertiefungen im Bereich < 1 µrn ist die Anwendung dieses Verfahrens jedoch nicht mehr sinnvoll, da die zur Ermittlung des Profilschnittes verwendete Tastnadel mit einem Radius r = 3 µm diese Feinheiten nicht mehr aufzulösen vermag.According to DIN 4762, the profile load share tp is determined by evaluating profile sections. However, the use of this method is no longer sensible for surfaces with extremely fine cut-outs or depressions in the range <1 µrn, since the stylus with a radius r = 3 µm used to determine the profile cut can no longer resolve these subtleties.

Da die erfindungsgemäßen Maschinenbauteile einen Mittenrauhwert < 0,3 µm aufweisen, erfolgt die Ermittlung des Profiltraganteils in Abweichung von der genannten DIN-Norm durch Auswertung photographischer Aufnahmen (Auflichtmikroskopie). Hierbei erscheinen alle Vertiefungen in der Oberfläche (alle nicht ebenen Bereiche) auf Grund der nicht gerichteten Licht-Rückstreuung als dunkle Zonen.Since the machine components according to the invention have a mean roughness value of <0.3 μm, the proportion of profile load is determined in deviation from the DIN standard mentioned by evaluating photographic recordings (reflected light microscopy). Here, all depressions in the surface (all non-flat areas) appear as dark zones due to the non-directional light backscattering.

Bei den erfindungsgemäßen Maschinenbauteilen ist deshalb immer ein Profiltraganteil zu verstehen, der in Analogie zur DIN 4762 definiert ist als :

Figure imgb0001

  • In = tragende Länge = helle Länge,
  • I = Bezugsstrecke.
In the case of the machine components according to the invention, therefore, a proportion of the profile load is always to be understood, which is defined in analogy to DIN 4762 as:
Figure imgb0001
  • In = supporting length = light length,
  • I = reference distance.

Zur Auswertung werden je 10 Bezugsstrecken von 0,5 mm Länge herangezogen.For each evaluation, 10 reference sections with a length of 0.5 mm are used.

Durch den geringen Traganteil ist die Reibung der mit einem weiteren Maschinenbauteil in Eingriff stehenden erfindungsgemäßen Maschinenbauteile erheblich geringer. Am Beispiel eines Steuerelementes, dessen Ventilscheiben aus erfindungsgemäßen Maschinenbauteilen bestehen, ergibt sich dabei überraschenderweise, daß die Dichtigkeit des Steuerelementes durchaus mit der Dichtigkeit eines Steuerelementes vergleichbar ist, das mit bisher bekannten Ventilscheiben ausgerüstet ist. Durch die vorliegende Erfindung ist damit erstmals die Überwindung des bestehenden Vorurteils gelungen, wonach eine hohe Dichtigkeit eines aus keramischen Ventilscheiben hergestellten Steuerelementes nur dann erzielbar war, wenn die Ventilscheiben eine geringe Rauhigkeit, verbunden mit einem hohen Traganteil aufwiesen.Due to the low load-bearing component, the friction of the machine components according to the invention which are in engagement with another machine component is considerably lower. Using the example of a control element whose valve disks consist of machine components according to the invention, it surprisingly results that the tightness of the control element is comparable to the tightness of a control element which is equipped with previously known valve disks. The present invention thus for the first time succeeded in overcoming the existing prejudice, according to which a high tightness of a control element made of ceramic valve disks could only be achieved if the valve disks had a low roughness combined with a high load-bearing component.

Ein weiterer, in-der neuartigen Mikrostruktur der Oberfläche liegender Vorteil der erfindungsgemäßen Maschinenbauteile besteht darin, daß diese ohne zusätzliches Schmierfett eingesetzt werden können, wobei ihre volle Funktionsfähigkeit auch nach längerer Zeitdauer noch erhalten bleibt.Another advantage of the novel microstructure of the surface of the machine components according to the invention is that they can be used without additional grease, their full functionality being retained even after a long period of time.

In einer besonders bevorzugten Ausführungsform enthalten die erfindungsgemäßen Maschinenbauteile 7 bis 16 Gew.% Zirkonoxid.In a particularly preferred embodiment, the machine components according to the invention contain 7 to 16% by weight of zirconium oxide.

Der Mittenrauhwert Ra liegt vorzugsweise zwischen 0,1 und 0,03 µm.The average roughness Ra is preferably between 0.1 and 0.03 μm.

Die erfindungsgemäßen Maschinenbauteile können als weitere oxidkeramische Werkstoffe Aluminiumoxid, Titanoxid und Mullit enthalten, ganz besonders bevorzugt ist davon das Aluminiumoxid, das vorteilhaft zu mindestens 75 Gew.% enthalten ist.The machine components according to the invention can contain aluminum oxide, titanium oxide and mullite as further oxide-ceramic materials, very particularly preferred is the aluminum oxide, which is advantageously contained at least 75% by weight.

Für das verwendete Aluminiumoxid hat sich eine Teilchengröße von < 5 µm und für das Zirkonoxid eine Teilchengröße von 0,2 bis 2 µm als optimal geeignet erwiesen, für die Erzielung der gewünschten Oberflächencharakteristik.For the aluminum oxide used, a particle size of <5 μm and for the zirconium oxide a particle size of 0.2 to 2 μm have proven to be optimally suitable for achieving the desired surface characteristics.

Zugesetzt werden können dem Aluminiumoxid noch geringe Mengen eines Kornwachstumshemmers und Sinterhilfsmittels, wobei besonders eine Zugabemenge von 0,05 bis 0,25 Gew.% Magnesiumoxid geeignet ist.Small amounts of a grain growth inhibitor and sintering aid can also be added to the aluminum oxide, a quantity of 0.05 to 0.25% by weight of magnesium oxide being particularly suitable.

Rein äußerlich unterscheiden sich die erfindungsgemäßen Maschinenbauteile von den bisher bekannten dadurch, daß die Oberfläche nicht das hochglänzende Aussehen der bisher bekannten Maschinenbauteile aufweist, sondern ein mehr mattglänzendes Aussehen besitzt. Die äußerlich mit bloßem Auge bereits erkennbaren Unterschiede sind auf die unterschiedliche Mikrostruktur der Oberfläche zurückzuführen, wobei ein hoher Profiltraganteil eine hochglänzende Oberfläche ergibt, während ein geringer Traganteil mit einer Vielzahl von Einschnitten - von allerdings sehr geringer Tiefe - den erfindungsgemäßen Maschinenbauteilen ein mattglänzendes Aussehen der Oberfläche verleiht. Diese andersartige Struktur in der Oberfläche ist allerdings nur dann erreichbar, wenn die Oberfläche so bearbeitet wird, daß an der Oberfläche der erfindungsgemäßen Maschinenbauteile tatsächlich eine Umwandlung des eingelagerten Zirkonoxids in die monokline Form stattfindet. Diese Umwandlung der an der Oberfläche oder unmittelbar unterhalb der Oberfläche sich befindenden eingelagerten Zirkonoxidteilchen erfolgt auf Grund der spannungsinduzierten Phasenumwandlung infolge der in diesem Oberflächenbereich bei der Bearbeitung mit Diamantkorn (Schleifen und/oder Läppen) wirksam werdenden hohen mechanisch/thermischen Belastung auf die eingelagerten Zirkonoxidteilchen sowie deren unmittelbare Umgebung.Externally, the machine components according to the invention differ from those previously known in that the surface does not have the high-gloss appearance of the previously known machine components, but has a more matt-gloss appearance. The differences that can already be seen externally with the naked eye can be attributed to the different microstructure of the surface, with a high proportion of profile support resulting in a high-gloss surface, while a low proportion of support with a large number of cuts - but of very small depth - gives the machine components according to the invention a matt-glossy appearance of the surface gives. However, this different structure in the surface can only be achieved if the surface is processed in such a way that a conversion of the incorporated zirconium oxide into the monoclinic form actually takes place on the surface of the machine components according to the invention. This conversion of the embedded zirconium oxide particles located on the surface or immediately below the surface takes place due to the stress-induced phase transition as a result of the high mechanical / thermal stress on the incorporated zirconium oxide particles, which becomes effective in this surface area during processing with diamond grain (grinding and / or lapping) their immediate surroundings.

Im Gegensatz dazu verharren die tiefer im Inneren der Maschinenbauteile befindlichen eingelagerten Zirkonoxidteilchen in der metastabilen tetragonalen Modifikation, da einerseits die durch den Schleif- bzw. Läpp-Prozeß aufgebrachte mechanisch/thermische Belastung in größerer Tiefe stark abnimmt und andererseits das Umklappen dieser tetragonalen Zirkonoxidteilchen in die monokline Modifikation, die unter Volumenzunahme erfolgt, durch die starke allseitige Einbindung der Teilchen (Druckkräfte) in die übrigen Werkstoffkomponenten behindert wird.In contrast, the embedded zirconium oxide particles located deeper inside the machine components remain in the metastable tetragonal modification, since on the one hand the mechanical / thermal load applied by the grinding or lapping process decreases sharply at greater depth and on the other hand the folding of these tetragonal zirconium oxide particles into the monoclinic modification, which takes place with an increase in volume, is hindered by the strong all-round integration of the particles (compressive forces) in the other material components.

Die Figur zeigt ein Maschinenbauteil in Form einer Ventilscheibe in der erfindungsgemäßen Zusammensetzung, ohne daß die Erfindung auf diese Ausführungsform beschränkt ist.The figure shows a machine component in the form of a valve disk in the composition according to the invention, without the invention being restricted to this embodiment.

Mit 1 ist die Ventilscheibe bezeichnet. Am Rande weist die Ventilscheibe 1 Ausnehmungen 2 auf. Mit 3 bzw. 3' sind die Durchlaßöffnungen für die zu mischenden Flüssigkeitsströme und mit 4 der Auslauf des gemischten Flüssigkeitsstromes bezeichnet. Bei 5 ist in schematisierter Form das Innere der Ventilscheibe dargestellt, in dem bei Raumtemperatur das eingelagerte Zirkonoxid in metastabiler, tetragonaler Modifikation vorliegt.The valve disk is designated by 1. At the edge, the valve disk 1 has recesses 2. With 3 or 3 'the passage openings for the liquid streams to be mixed and with 4 the outlet of the mixed liquid stream are designated. 5 shows the interior of the valve disc in a schematic form, in which the embedded zirconium oxide is present in a metastable, tetragonal modification at room temperature.

Die nachfolgenden Beispiele verdeutlichen die Erfindung, ohne daß die Erfindung auf die Beispiele beschränkt ist.The following examples illustrate the invention without restricting the invention to the examples.

Beispiel 1example 1

330 g Zirkonsilikatpulver (ZrSi04) mit einer mittleren Korngröße von < 5 µm und 700 g Aluminiumoxidpulver (AI203) mit einer mittleren Korngröße von < 3 J.Lm werden in einem hochwirksamen Mahlaggregat unter Zusatz von Wasser gemischt und vermahlen, wobei sich eine spezifische Oberfläche der Pulvermischung von ca. 13 m2/g ergab. Unter Zusatz eines wasserlöslichen Bindemittels wird das entstandene Granulat bei einem Preßdruck vom 1 000 kp/cm2 zu Ventilscheiben geformt. Die Form der Ventilscheibe entspricht der in der Figur dargestellten.330 g of zirconium silicate powder (ZrSi0 4 ) with an average grain size of <5 µm and 700 g of aluminum oxide powder (Al 2 0 3 ) with an average grain size of <3 J.Lm are mixed and ground in a highly effective grinding unit with the addition of water a specific surface area of the powder mixture of approx. 13 m 2 / g resulted. With the addition of a water-soluble binder The resulting granules are shaped into valve disks at a pressure of 1,000 kp / cm 2 . The shape of the valve disc corresponds to that shown in the figure.

Die Scheiben werden in einem gasbeheizten Ofen bei einer Temperatur von 1 550 °C und einer Haltezeit bei dieser Temperatur von 3 Stunden zu dichten Körpern gebrannt. Diese Körper besitzen infolge der Umsetzungsreaktion

Figure imgb0002
die Endzusammensetzung : Mullit + Zirkonoxid sowie überschüssiges Aluminiumoxid.The disks are fired in a gas-heated furnace at a temperature of 1,550 ° C. and a holding time at this temperature of 3 hours to form dense bodies. These bodies have as a result of the reaction
Figure imgb0002
 the final composition: mullite + zirconium oxide and excess aluminum oxide.

Nach dem Läppen mit Diamantkorn von 5 µm auf einer gerillten, ebenen Stahlscheibe besitzen die Ventilscheiben eine mattglänzende Oberfläche mit einem extrem niedrigen Profiltraganteil, der durch lichtoptische Auswertung mit 15 % ermittelt wurde. Die Mittenrauhigkeit Ra wurde mit 0,05 µm gemessen.After lapping with 5 µm diamond grain on a grooved, flat steel disc, the valve discs have a matt, glossy surface with an extremely low profile percentage, which was determined to be 15% by optical analysis. The center roughness Ra was measured at 0.05 µm.

Beispiel 2Example 2

900 g eines für die Herstellung von gesinterter, hochdichter und feinkörniger A1205-Keramik geeigneten Aluminiumoxidpulvers mit einem Zusatz von 0,1 Gew.% Magnesiumoxid und einer mittleren Teilchengröße von < 5 µm werden mit 100 g monoklinem (unstabilisiertem) Zirkonoxidpulver mit einer mittleren Teilchengröße von < 1 µm unter Zusatz von Wasser gemahlen und vermischt.900 g of an aluminum oxide powder suitable for the production of sintered, high-density and fine-grained A1 2 0 5 ceramic with an addition of 0.1% by weight of magnesium oxide and an average particle size of <5 μm are mixed with 100 g of monoclinic (unstabilized) zirconium oxide powder with a average particle size of <1 µm ground and mixed with the addition of water.

Der gemahlene Schlicker wird unter Zusatz eines üblichen wasserlöslichen Bindemittels sprühgetrocknet. Das so erhaltene Granulat wird bei einem Preßdruck von ca. 1 500 kp/cm2 in einer hydraulischen axialwirkenden Presse zu einer Ventilscheibe entsprechend der Figur verpreßt.The ground slip is spray-dried with the addition of a conventional water-soluble binder. The granules obtained in this way are pressed at a pressure of approximately 1,500 kg / cm 2 in a hydraulic, axially acting press to form a valve disk as shown in the figure.

Diese Ventilscheibe wird in einem gasbeheizten Ofen bei einer Temperatur von 1 600 °C und einer Haltezeit bei dieser Temperatur von 5 Stunden dichtgesintert.This valve disc is densely sintered in a gas-heated furnace at a temperature of 1,600 ° C. and a holding time at this temperature of 5 hours.

Nach dem wie in Beispiel 1 durchgeführten Läppverfahren zeigen die Ventilscheiben eine mattglänzende Oberfläche mit einem Profiltraganteil von 20 % und eine Mittenrauhigkeit Ra = 0,08 wm. Die Ebenheit der bearbeiteten Ventilscheiben ist < 2 Lichtbanden.According to the lapping process carried out as in Example 1, the valve disks have a matt, glossy surface with a profile percentage of 20% and an average roughness Ra = 0.08 wm. The flatness of the machined valve disks is <2 light bands.

In einer geeigneten Prüfapparatur, bei der ein schlagartiger Austausch des Kalt- und Heißwasserstromes vorgenommen werden kann, und bei der die Verhältnisse einer sanitären Mischarmatur simuliert werden können, wurd eine gemäß Beispiel 2 hergestellte Ventilscheibe mit einer formgleichen Ventilscheibe aus reiner Aluminiumoxidkeramik auf ihr Thermoschockverhalten verglichen. Die gemessene Thermoschockbeständigkeit der reinen Aluminiumoxidkeramischeibe lag dabei bei ΔT 110 °C, während die Ventilscheibe gemäß Beispiel 2 eine Thermoschockbeständigkeit von ΔT 110°C aufwies.In a suitable test apparatus, in which an abrupt exchange of the cold and hot water flow can be carried out, and in which the conditions of a sanitary mixer tap can be simulated, a valve disk manufactured according to Example 2 was compared with a valve disk of identical shape made of pure aluminum oxide ceramic for its thermal shock behavior. The measured thermal shock resistance of the pure aluminum oxide ceramic disc was ΔT 110 ° C, while the valve disc according to Example 2 had a thermal shock resistance of ΔT 110 ° C.

Eine Untersuchung der Verschiebekraft bzw. des Verschiebemoments ergab für gemäß Beispiel 2 und Fig. 1 hergestellte Ventilscheiben und solchen aus reiner Aluminiumoxidkeramik folgende Werte :

Figure imgb0003
An examination of the displacement force or the displacement torque showed the following values for valve disks manufactured according to Example 2 and FIG. 1 and those made of pure aluminum oxide ceramic:
Figure imgb0003

Die Prüfung der Verschiebekräfte erfolgte auf einer für diesen Zweck entwickelten Apparatur mit Wasser von 13,5 bzw. 60 °C, die ermittelten Werte beziehen sich auf die reine Reibpaarung, d. h. Reibverluste der Mechanik der Armatur wurden in Abzug gebracht. Die Scheiben wurden mit 30 kp gegeneinander gepreßt. Zur Messung wurden Scheiben verwendet, die vorher in 200 000 Zyklen, das entspricht einer Benutzungsdauer von ca. 10 Jahren, betätigt worden waren.The displacement forces were tested on an apparatus developed for this purpose with water at 13.5 or 60 ° C, the values determined relate to the pure friction pairing, i.e. H. Frictional losses of the valve mechanics were deducted. The disks were pressed against each other at 30 kp. Discs were used for the measurement, which had previously been operated in 200,000 cycles, which corresponds to a service life of approximately 10 years.

Claims (4)

1. A mechanical component which comprises constituents of ceramic oxide material and which has a sealing action and is in frictional engagement, such as, for example, a slide ring for an axial sliding bearing seal or a valve disc for mixing valves, especially for sanitary mixing assemblies, characterised by the following features :
a) the mechanical component contains from 3.0 to 25 % by weight of zirconium oxide and/or hafnium oxide, which is incorporated in homogeneous distribution in the other material constituents and which is predominantly in metastable, tetragonal modification at room temperature within the mechanical component but is in monoclinic modification on the surface of the mechanical component,
b) a profile bearing ratio of from 10 to 40 % obtained by surface treatment, such as grinding and lapping,
c) a mean roughness value Ra for the mechanical component of less than 0.3 µm.
2. A mechanical component according to claim 1, characterised in that the proportion of zirconium oxide and/or hafnium oxide is from 7 to 16 % by weight.
3. A mechanical component according to claim 1 or 2, characterised in that it has a mean roughness value Ra of from 0.1 to 0.03 µm.
4. A mechanical component according to any one of claims 1 to 3, characterised in that it has an aluminium oxide content of at least 75 % by weight.
EP19810104408 1980-07-05 1981-06-09 Machine element composed of ceramic oxide material Expired EP0043456B1 (en)

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DE19803025596 DE3025596A1 (en) 1980-07-05 1980-07-05 VALVE DISC MADE OF OXIDE CERAMIC MATERIAL

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JPS5751173A (en) 1982-03-25
DE3163369D1 (en) 1984-06-07
US4420142A (en) 1983-12-13
EP0043456A1 (en) 1982-01-13
DE3025596A1 (en) 1982-02-25

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